1. Field of Invention
The present invention relates to an expansion structure of memory module slots, and more particularly, to an expansion structure of memory module slots that is capable of assembling more memory modules onto a motherboard.
2. Related Art
A central processing unit (CPU) of a computer host takes a random access memory (RAM) as a data storage area. Computing results and program instructions of the CPU are all stored in the RAM, and the data stored in the storage area is available once it is required by executing a program.
Currently, the computer host has more and more powerful functions, and accordingly, the requirement for the calculation function is increasingly high, and thus, more RAMs are demanded. FIG. 1A is a side view of a memory module being plugged in a motherboard, and FIG. 1B is a schematic isometric view of the memory module. Referring to FIGS. 1A and 1B, a north bridge chip 21a and a plurality of memory module slots 22a adjacent to the north bridge chip 21a are disposed on a motherboard 20a. Memory modules 50a may be plugged in the memory module slots 22a by golden fingers. Each of the memory modules 50a further includes a printed circuit board (PCB) 51a and a plurality of memories 52a, and the memories 52a are respectively disposed on two end surfaces of the PCB 51a. The north bridge chip 21a is mainly used to control the signal transmission between the CPU and the memory modules 50a. 
Therefore, under the current situation of increasing data processing speed and increasing large data quantity for being processed, the capacity of the corresponding memory modules also becomes higher, and meanwhile, more memory module slots are required for more memory modules to be plugged in. However, the memory module slots are directly disposed on the surface of the motherboard, and thus, if more memory modules are intended to be assembled, more memory module slots have to be disposed on the surface of the motherboard, and thereby occupying more area of the motherboard. Under the limited assembling area of the motherboard, the assembling of other electronic elements is affected. On the other hand, the area of the motherboard must be enlarged to accommodate more memory module slots, which, however, causes an increase in the volume of the computer host, and thereby running against the trend for the computer host to become light in weight and small in size.